Snowplough with adjustable blade

ABSTRACT

A SNOWPLOUGH INCLUDES A DEVICE WHICH PREVENTS INJURY TO THE PLOUGH BLADE WHEN THE PLOUGH BLADE ENCOUNTERS A SOLID OBSTACLE BY MOVING THE BLADE UPWARD AND DOWNWARD OR BY TILTING THE SAME ABOUT A HORIZONTAL AXIS.

United States Patent Inventor Alfred Schmidt, Jr.

St. Blaslen/Bhck Forest, Germany Appl. No. 794,643 Filed Jan. 28, 1969 Patented June 28, 1971 Assignee lng. Alfred Schmidt St. Blasien/Black Forest, Germany Priority Mar. 1, 1968 Germany SNOWPLOUGH WITH ADJUSTABLE BLADE 8 him D F C 5 rawmg 85 Assistant ExaminerClifford D. Crowder US. Cl 172/264, n and n 172/271, 172/801, 172/71 1, 172/794, 37/41 Int. Cl A01b 61/00,

E021 3/76, EOlh 5/06 ABSTRACT: A snowplough includes a device which prevents Field of Search 37/41, 42, injury to the plough blade when the plough blade encounters a 44-50; 172/801-807, 71 1, 794, 265, 27], solid obstacle by moving the blade upward and downward or 266-268, 264 by tilting the same about a horizontal axis.

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1' I i --l7o O 2 8 L5 10 z 9 I l 2 3 7 37/42 Primary ExaminerRobert E. Pulfrey PATENTED M28 1971 SHEET 1 [IF 2 FIG.

INVENTOR ALFRED SCHMIDT JR FIG. 2

ATTORNEYS PATENTEUJUHZBIHYI 3587751 sum 2 BF 2' INVENTOR Wi x 7/11.?

ATTORNE Y5 ALFRED SCHMIDT JR.

SNOWPLOUGII WITI-I ADJUSTABLE BLADE Snow clearing blades have been mounted on upper and lower pivot levers in order that the lower edge of the blade when encountering an obstacle might performan evading upward and backward movement. For this purpose, the lower pivot levers are inclined upward from a support member toward the blade and the latter is urged by means of a tension spring against the road surface. This prior art arrangement makes it possible to adjust the clearing blade relative to the road surface and permits the blade to slip over low obstacles on the road without injury to the plough.

However, when encountering larger obstacles such as curbstones, for example, the blade is not able to rise over the obstacle because of the limited range of upward and backward movement of the protective device. When higher obstacles with steep front edges are encountered there is a probability of damage both to the blade and to the suspension device.

To protect snowploughs against large obstacles lying on the ground there has been also known an arrangement wherein the clearing blade is tiltably disposed on a horizontal axle rod extending behind the blade and mounted on a support member. During the normal operation of the plough, the tilting movement of the blade is blocked by a shear pin or the like. When an obstacle is struck, the resulting impact force shears of the pin and tilts the blade so that the lower portion thereof can evade the obstacle. Although the latter arrangement protects the snowplough blade against damage, it has the disadvantage that the blade cannot be automatically readjusted to the road surface during the snow clearing operation. After relative responding to an impact, the operation of the snowplough must be interrupted to restore the original working position of the blade which has been angularly displaced and to replace the blocking shear pin.

An object of the present invention is to provide a snowplough having a blade which is adapted for being continuously and automatically readjusted in response to conditions of the road surface.

Another object of the present invention is to provide a snowplough which is capable of overcoming lower obstacles on the ground without interrupting the clearing operation and which even when encountering higher obstacles can slip over the same without damage.

According to the present invention, the above objects are attained by means in which the blade is combined with a conventional linkage having lower and upper pivot levers coupled with a support member and a tension spring element. The lower pivot lever is inclined upward and the upper pivot lever downward in relation to the blade. The support member is tiltably mounted on a horizontal axle extending parallel to the blade and the support member is held in working position by pressure responsive locking means which upon the application of a predetermined force become unlocked and allow the blade to tilt about the axle.

Due to the actionof the pivot levers and of the spring element the blade of the snowplough of this invention can continuously adjust itself to an uneven road surface and slip over smaller obstacles thereupon. Immediately upon the overcoming of the obstacle, it restores its working contact with the road. At the same time, when encountering a higher obstacle, the snowplough blade according to the present invention, can evade the same by tilting the support member about the horizontal axle so that the entire blade arrangement is securely protected against damage.

Within the scope of the present invention is also the embodiment of the snowplough having a multisectional movable blade. In this embodiment the blade sections are arranged side by side and linked together by a separate pivot lever linkage to corresponding support members tiltably mounted on a common horizontal axle or rod. The blade arranged in this manner insures a particularly effective adjustment of the plough to various conditions of the road surface during the clearing operation.

As known from practice, larger obstacles, such as curbstones and the like, occur at marginal zones of the road only and, consequently, it is advantageous to design the horizontally divided blade in such a way that only two end sections thereof are disposed on the tiltable support member. The support members for the intermediate blade sections can be rigidly connected to the horizontal axle since in the middle area of the road there is normally no need for taking any measures for protection against higher obstacles; the functional range of the pivot levers will thus be quite sufficient in that area.

The support members which are tiltably arranged on the axle are hold in a firm working position by means of shear pins or the like. The shear pins are dimensioned so as to protect the blade against a predetermined counterforce. For this purpose there may be also employed protective spring means which are disposed between the axle and the support members. These spring means must be biased in such a way that the pressure against the lower portion of the blade will not cause the tilting of the support member prior to the displacement of the pivot levers to their uppermost limit position. In other words, the protective spring means must not act before the tension spring of the blade is set back along the entire path of movement of the blade linkage.

In another variation, the support member can be provided with a lock pawl secured to the axle so as to unlock the former when a predetermined excess force is applied against the blade, thus permitting the support member to tilt about the axle. The aforementioned lock pawl can be combined with an auxiliary restoring spring means which makes it possible that the tilted blade, as soon as a higher obstacle has been passed, returns together with its support member to the normal working position and the lock pawl becomes locked again.

In order that the present invention may be readily understood, it will now be described with reference to the accompanying drawings, in which:

FIG; 1 is a side elevational view of a snowplough of this invention in a working position;

FIG. 2 illustrates the snowplough of FIG. 1 wherein the blade is in its uppermost position;

FIG. 3 is a side elevational view of the snowplough of this invention having the blade divided into a number of blade sections whereby one of these blade sections is tilted by an obstacle;

FIG. 4 is a schematical plan view of a snowplough having a multisectional blade with a tilted end section; and

FIG. 5 is a front elevational view of the device with the snowplough removed for purpose of clarity.

In the FIGS. the same components are identified by the same reference numerals.

In FIGS. 1 and 2, the snowplough consists of a blade I which is linked by an upper pivot lever 2 and a lower pivot lever 5 to a support member 4. The support member 4 is tiltably supported on a horizontal axle or rod 5 which is parallel to the blade 1. The horizontal axle 5 is rigidly connected with a retainer device 6. The lower pivot 3 at the normal working position of the blade is inclined upward, in the direction from the support member toward the blade, so that when the lower edge of the blade encounters an obstacle the entire blade is moved backward and upwardly against the force of the tension spring 7 which is arranged between the upper portion of the blade and the horizontal axle. The movement of blade 1 is delimited by two limit stops 8 and 9 which are integral with the side wall of the blade and which cooperate with the nose 10 which is integral with the axle 5 and which protrudes between the stops. At the normal working position olthe snowplough, the nose It) abuts, due to the action of tension spring 7, the upperlimit stop 8 (FIG. 1). However, as seen in FIG. 2, the pivotal arrangement of the levers 2 and 3 allows the blade to pass over a smaller obstacle OB having a height within the range of the distance between limit stops 8 and 9. At the raised position of the blade, the nose l0 abuts the lower limit stop 9.

FIG. 3 shows another variation of the invention comprising a multisectional blade. The blade sections 11, 11a are disposed side-by-side and are coupled through pivotable levers 2, 3 and 2a, 3a to respective support members 14, 14a. The support members are disposed on a horizontal axle 15 which is firmly connected to the retainer means 16. The retainer means 16 comprises pivotally mounted control arms 22 and 23 arranged for parallel movement on the attachment frame 25 of a carrier vehicle. The vertical movement of the retainer means 16 is controlled by the aid of a lifting device 24 which is hinged between an elevated portion of the retainer and the lower control arm 23. The support members 14, 14a are tiltably supported on axle l and held at upright working position by shear means 17. When encountering a higher obstacle HOB which the blade is unable to overcome by means of the pivot levers 2, 3, the resulting force causes the shear pin 17 to break off and the support member section 14 is tilt forward about axle 15. As illustrated in FIG. 5 a torsion spring 27 which is secured at one end to the support member 4 and at the other end to the shaft 5 can be utilized in place of the shear pins 17. FIG. 4 shows in a plan view another modification of the multisectional blade. Corresponding support member sections 14:: to He are coupled to the blade sections by pivotable levers and are supported on the axle 5 which is rigidly connected with the retainer means 6. The right-hand support member 140 with blade section 11a is shown in a tilted condition which results after encountering a higher obstacle HOB at the border area of the road.

FIG. 5 discloses a torsion spring 27 on shaft 5, the spring being connected at one end to supporting member 4 and at the other end to the retainer device 6. Thus, when the maximum spring force of the spring 7 is exceeded, as shown in FIG. 2, upon striking a major obstacle, the blade 1, together with pivoting levers 2 and 3, the support member 24, and the pivot lever or shaft 5 pivots forward counter to the force of the torsion spring 27, as is shown in FIG. 3, whereby the HOB is over come.

lclaim:

l. A plough which is adapted to be coupled to a vehicle, said plow including blade means, support means, upper and lower lever arm means pivotably connecting said blade means to said support means to provide for vertical movement of said blade means, means to limit said vertical movement to a predetermined distance, said lower lever arm means being inclined upward from the support means to said blade means, shaft means extending in a direction substantially parallel to said blade means and supporting said support means, means for maintaining said support means in a fixed rotational relationship relative to said shaft means when said blade means is at a height above the surface being plowed less than said predetermined distance and means for allowing said support means to freely rotate about said shaft means when the height of said blade above said surface exceeds said predetermined distance.

2. The plough according to claim 1 wherein said blade is divided into a number of blade sections, each of the blade sections having a corresponding support member section. I

3. The plough according to claim 2 wherein said support member sections include end sections and at least one section intermediate said end sections wherein the intermediate section is fixedly mounted to said shaft.

4. The plough according to claim 1 wherein said maintaining means is a shear pin operatively arranged between said support means and said shaft means.

5. The plough according to claim 4 wherein said shaft means includes an outwardly extending nose portion and said blade means includes a stop for engaging said nose portion when said blade means is at said predetermined height whereby the further elevation of said blade means results in said shaft means rotating relative to said support means, shearing said shear pin, and thereby allowing said support means to freely rotate about said shaft means.

6. The plough according to claim 1, wherein said plow further includes means for urging said blade means downwardly into contact with the surface being plowed.

7. The plough according to claim 6, wherein said urging means is a torsion spring operatively arranged between said blade means and said shaft means to force the blade against the road surface.

8. The plough according to claim 1, wherein said plow further comprises retainer means for mounting said plow to a vehicle and wherein said maintaining means comprises a torsion spring operatively arranged between said support means and said shaft means. 

